The exchanges in the Commons yesterday vividly illustrated how the world has changed completely for all the political parties after the government's unprecedented £500bn bank rescue plan.

The chancellor, Alistair Darling, found himself in the curious position of lecturing the Conservative party on the dangers of too much state intervention and rebuffing a call from his Tory counterpart, George Osborne, for the government to block bonuses to reckless bank executives. "We have to make sure that we [do] not get ourselves into a position where we think we can sit in a boardroom and take all the decisions for everyone," said Darling.

Vince Cable, the Liberal Democrats Treasury spokesman, savoured the moment. "I have been stunned by the sudden conversion of the champions of the bonus culture to advocates of 1970s style incomes policy," he said.

All three leaders are suddenly working in a very different political landscape.

Gordon Brown, who spent six months resisting the inevitable nationalisation of Northern Rock because he was so fearful of heralding a return to Labour's past as the champion of nationalisation, has been handed a lifeline. A few weeks after members of the cabinet were considering triggering his downfall, he has secured his position in the medium term by virtue of being at the centre of a financial storm.

"This has given the Labour party - and Gordon - a chance to recover and we should grab it," one senior member of the cabinet told the Guardian.

The extent and enduring nature of the crisis has led Brown to overcome fears that state intervention would mark a return to the 1970s. Ministers can now preside over the semi-nationalisation of big banks without fear of being mocked.

The Conservatives are also having to come to terms with dramatically different circumstances. David Cameron faces deep challenges on two levels. Firstly, he faces the same questions being posed to all centre-right parties across the world - and which appear to be inflicting such damage on John McCain's presidential ambitions. The Tories and the US Republicans are being asked what the champions of light regulation have to say after the spectacular failure of this approach.

That is why the Tories called for curbs to executive pay yesterday, although they argue this is entirely in keeping with their record in protecting taxpayers' money.

Secondly, the Tories will have to examine their own tactics. Cabinet ministers believe Cameron tore up political convention by taking part in a briefing on privy council terms last week, in which the government explained its plans in private. The Tory leader is then alleged to have demanded the introduction of these plans over the weekend on television so that he could claim credit.

"The Tories have behaved outrageously and resorting to students' union tactics. They need to grow up," one cabinet minister said. The Conservatives dismiss this and say Cameron's thoughts over the weekend were being widely discussed.

MPs on all sides of the Commons expressed astonishment at the changed landscape. The Liberal Democrat leader, Nick Clegg, said: "There can be no doubt today marks a fundamental shift in the way we view banks and, in turn, the obligations banks have to the public must change for good: they must serve the public interest as well as their own commercial interests."

Colin Burgon, the Labour MP for Elmet, saw it a different way. "What I see is the invisible hand of the market putting its hand into the pocket of the taxpayer and taking £50bn away and maybe putting two fingers up as well."

George Galloway, the Respect MP for Bethnal Green and Bow, added: "Well, the Liberals sound like Labour and the Conservatives like Communists - the kaleidoscope has definitely been shaken. But while the pieces are in flux, why don't we reorder this world? What's so wrong about the taxpayer having a seat in the boardroom?"

How they've performed

Gordon Brown

Odd though it may seem, the destruction of the global financial system has put a spring in the prime minister's step. On the plus side, he was proved right about the absence of proper international regulation, he successfully worked his international contacts and now hopes his comprehensive and expensive plan will be the template for other countries. But he faces a borrowing hangover, and a brutal day of reckoning may await as recession nears. Verdict: Still in the balance

Alistair Darling

Calm, downbeat and often over-shadowed by his boss. The chancellor adopted a limited case-by-case response as the banks hit the rocks. A victim of leaks to the media about the rescue plans, he did not react quickly enough once details of the part-nationalisation plan drove share prices down. Verdict: Could have done better

George Osborne

Not a man born to consensus politics, the shadow chancellor opposed nationalising Northern Rock and this week tried to get ahead of the curve by backing part-nationalisation of banks before it was announced. Adopted a populist line on bank bonuses. Verdict: Inconsistent - he needs to show patience and sure judgment

Mervyn King

The Bank governor was blamed for precipitating the run on Northern Rock by promising to be lender of last resort. He also angered the City by taking a hardline approach to failing banks and belatedly promised guarantees to depositors. He is accused of having allowed a muddled regulatory regime to develop and has arguably been slow to cut interest rates, focusing on inflation. Verdict: Christmas cards may be in short supply this year